High-Strength Screw Spikes 1x5-1/8, 1x6, 1x7 inch (AREMA 2012)

In railway track structures, screw spikes are critical components that ensure a reliable connection between the rail and the sleeper. Unlike ordinary spikes, high-strength screw spikes feature precision-threaded designs and high-quality materials, enabling them to withstand the enormous longitudinal forces and dynamic impacts generated by train operations while maintaining long-term track geometry stability. On timber sleeper track with tie plates, the screw spike is the component that holds the whole assembly together.

What Do the Sizes 1x5-1/8, 1x6 and 1x7 Mean?

The specification format is shank diameter by overall length. A 1 x 5-1/8 inch screw spike has a 1 inch (25.4 mm) diameter shank and a 5-1/8 inch (about 130 mm) overall length; the 1 x 6 and 1 x 7 inch variants are the same diameter with longer shanks, about 152 mm and 178 mm respectively. The series is designed to accommodate varying sleeper thicknesses, load classes and installation spaces, so the track engineer can select the length that gives the required embedment in the sleeper while suiting the tie plate and rail foot geometry.

Why Screw Spikes Instead of Dog Spikes?

Metal railway screw spikes cost more to manufacture than dog spikes, but they offer the decisive advantage of greater fixing power: approximately twice the holding force of a dog spike of similar size. The threaded shank grips the timber along its full embedded length, resists withdrawal under uplift and resists the longitudinal forces of braking and traction. Screw spikes can also be used in combination with spring washers, which maintain tension and absorb the vertical movement of the rail under traffic.

Specification and Materials

High-strength screw spikes to the AREMA 2012 specification are manufactured from quality carbon or alloy steels. Common raw materials include Q235, 35 steel, 45 steel, 40Mn2 and 20MnSi, and the finished fasteners are produced to property classes from 4.6 up to 8.8, so the strength grade can be matched to the axle load and sleeper material. The threaded portion, head geometry and point design follow the specified standard, and the products are 100 percent inspectable for thread profile, hardness and coating integrity.

Surface Finishes and Corrosion Protection

The choice of finish depends on the environment and the service life target. Plain oiled spikes are the economical choice for dry, low-corrosion sites; black or colour paint adds basic protection; zinc plating gives a bright, uniform coating for moderate exposure; and hot-dip galvanizing provides the thickest zinc layer for coastal, tropical and heavy-haul environments. Because the spike is embedded in timber and exposed to the elements at the head, coating quality at the head and thread transition is what decides the corrosion life.

Dog Spikes for Comparison

Dog spikes, also called cut spikes, remain common on secondary and industrial timber track. Typical sizes include 5/8 x 6 inch, 9/16 x 5-1/2 inch, 3/8 x 3-1/2 inch and 1/2 x 3-1/2 inch, produced in A3, Q235, 45 and 55 grades with finishes to customer requirement. They are cheaper and faster to install than screw spikes, but their holding power is lower, so on busier lines screw spikes are preferred.

Frequently Asked Questions

Q: What is a screw spike used for?

A screw spike fastens the rail, through the tie plate, to a timber sleeper. Its threaded shank resists vertical uplift and longitudinal rail movement, holding the track geometry under traffic.

Q: How much stronger is a screw spike than a dog spike?

Roughly twice as strong in withdrawal resistance, because the threads engage the timber along the full embedded length instead of relying on friction like a cut spike. This is why screw spikes are used on busier lines and sharper curves.

Q: What does AREMA 2012 mean in the specification?

It refers to the AREMA Manual for Railway Engineering, 2012 edition, which sets the dimensional, material and testing requirements for track fastening components in North American practice. The AREMA reference is a mark of the supply specification.

Q: What length screw spike do I need?

The length depends on the sleeper thickness, the tie plate and the required embedment. The 1 x 5-1/8 inch size suits standard timbers, while 1 x 6 and 1 x 7 inch provide deeper embedment for thicker sleepers or higher loads.

Q: Can screw spikes be used with spring washers?

Yes. A spring washer under the head maintains clamping tension as the timber compresses and the rail moves vertically, reducing loosening and extending the maintenance interval.

Q: Which finish should I choose for a coastal line?

Hot-dip galvanizing gives the thickest zinc layer and the best corrosion life in marine and high-humidity environments. For track-circuit areas, non-magnetic or insulated variants may be required, and the coating choice should be confirmed with the fastening specification.